Botulinum Toxin for Central Neuropathic Pain

Concomitant Botulinum Toxin Injections for Neurogenic Detrusor Overactivity and Spasticity-A Retrospective Analysis of Practice and Safety

As multiple indications for botulinum toxin injections (BTIs) can coexist for neurological patients, there are to date no description of concomitant injections (CIs) to treat both spasticity and neurogenic detrusor overactivity incontinence (NDOI) in patients with spinal cord injuries (SCIs) and multiple sclerosis (MS). We therefore identified patients followed at our institution by health data hub digging, using a specific procedure coding system in use in France, who have been treated at least once with detrusor and skeletal muscle BTIs within the same 1-month period, over the past 5 years (2017-2021). We analyzed 72 patients representing 319 CIs. Fifty (69%) were male, and the patients were mostly SCI (76%) and MS (18%) patients and were treated by a mean number of CIs of 4.4 ± 3.6 [1-14]. The mean cumulative dose was 442.1 ± 98.8 U, and 95% of CIs were performed within a 72 h timeframe. Among all CIs, five patients had symptoms evocative of distant spread but only one had a confirmed pathological jitter in single-fiber EMG. Eleven discontinued CIs for surgical alternatives: enterocystoplasty (five), tenotomy (three), intrathecal baclofen (two) and neurotomy (one). Concomitant BTIs for treating both spasticity and NDOI at the same time appeared safe when performed within a short delay and in compliance with actual knowledge for maximum doses.

Evaluation and Pharmacologic Management of Paroxysmal Sympathetic Hyperactivity in Traumatic Brain Injury

OBJECTIVE

Paroxysmal sympathetic hyperactivity (PSH) can occur in up to 10% of severe traumatic brain injury (TBI) patients and is associated with poorer outcomes. A consensus regarding management is lacking. We provide a practical guide on the multi-faceted clinical management of PSH, including pharmacological, procedural and non-pharmacological interventions. In addition to utilizing a standardized assessment tool, the use of medications to manage sympathetic and musculoskeletal manifestations (including pain) is highlighted. Recent studies investigating new approaches to clinical management are included in this review of pharmacologic treatment options.

CONCLUSION

While studies regarding pharmacologic selection for PSH are limited, this paper suggests a clinical approach to interventions based on predominant symptom presentation (sympathetic hyperactivity, pain and/or muscle hypertonicity) and relevant medication side effects.

Botulinum Toxin in Chronic Lateral Epicondylitis, from Tendon to Muscle Approach-A Review

BACKGROUND

Chronic lateral epicondylitis challenges the therapeutical approach; underlying mechanisms are incompletely understood; neuropathic pain and central and peripheral sensitization may explain the fact that botulinum toxin has been found to play a role in pain and function management.

METHODS

We searched the literature for MeSH terms: lateral epicondylitis or synonyms and botulinum toxin.

RESULTS

We found 14 papers containing trials on botulinum toxin injection into the tendon or into the extensor muscles (specifically, extensor carpi radialis brevis and extensor communis digitorum). We followed the administration pathways, doses, timing, and side effects.

CONCLUSIONS

With a chronic course, the focus of the therapy shifts from the afflicted tendon to the inserting muscles, as muscle contracture may create a vicious loop to perpetuate and aggravate the disease. Doses, timing, and side effects are discussed.

Case Report on Botulinum Toxin Treatment for Complex Regional Pain Syndrome in a Digit Reconstruction

Objective:To evaluate subcutaneous Botulinum toxin type A (BTX-A) efficacy in alleviating severe allodynia in complex regional pain syndrome (CRPS) type II post-digit reconstruction. Methods: After surgical debridement and flap reconstruction for post-traumatic necrosis, a CRPS type II patient received subcutaneous BTX-A. Assessments tracked symptom changes and daily life improvements. Discussion:There are various CRPS management modalities, including rehabilitation and pharmacology. The limited efficacy of conventional non-steroidal antiinflammatory drugs contrasts with promising subcutaneous BTX-A, offering rapid pain relief. Conclusion:Our case underscores the efficacy of subcutaneous BTX-A in CRPS type II, prompting further research and safe outpatient protocol development.

Aetiology, risk factors and treatment of typical and atypical pressure ulcers in patients with traumatic brain injury: A narrative review

Pressure ulcers are one of the leading complications in bedridden patients that result in multiple burdens on healthcare systems and patients (11 billion dollars/year). The prevalence of pressure ulcers in traumatic brain injury patients is 1.5-fold compared with the other bedridden patients. Moreover, critical traumatic brain injury patients who are admitted to the intensive care unit experience severe pressure ulcers and further complications. The motor/sensory disabilities and low supplementation and oxygenation to the pressured side were the main mechanisms of the typical pressure ulcers. Intellectual evaluation is the first essential step to prevent the development of pressure ulcers in high-risk patients. Till now, different scales, including Injury Scale Score and Braden Scale Score, have been provided to assess the pressure ulcer. Since low stages of pressure ulcers heal rapidly, traumatic brain injury patients require a periodical assessment to prevent further developments timely. Alongside different procedures provided to prevent and treat any pressure ulcer, traumatic brain injury patients required additional specific protections. For the first line, fast and efficient rehabilitation repairs motor/sensory disabilities and decreases the chance of pressure ulcer. Our review indicated that pressure ulcer in traumatic brain injury had several complex mechanisms that demand special care. Therefore, further studies are required to address these mechanisms and prevent their progression to typical and atypical pressure ulcers.

Potential role of Schwann cells in neuropathic pain

Neuropathic pain (NPP) is a common syndrome associated with most forms of disease, which poses a serious threat to human health. NPP may persist even after the nociceptive stimulation is eliminated, and treatment is extremely challenging in such cases. Schwann cells (SCs) form the myelin sheaths around neuronal axons and play a crucial role in neural information transmission. SCs can secrete trophic factors to nourish and protect axons, and can further secrete pain-related factors to induce pain. SCs may be activated by peripheral nerve injury, triggering the transformation of myelinated and non-myelinated SCs into cell phenotypes that specifically promote repair. These differentiated SCs provide necessary signals and spatial clues for survival, axonal regeneration, and nerve regeneration of damaged neurons. They can further change the microenvironment around the regions of nerve injury, and relieve the pain by repairing the injured nerve. Herein, we provide a comprehensive overview of the biological characteristics of SCs, discuss the relationship between SCs and nerve injury, and explore the potential mechanism of SCs and the occurrence of NPP. Moreover, we summarize the feasible strategies of SCs in the treatment of NPP, and attempt to elucidate the deficiencies and defects of SCs in the treatment of NPP.

Aging with spinal cord injury: A narrative review of consequences and challenges

Given the increase in life expectancy, aging with a pre-existing spinal cord injury (SCI) is becoming more common. This condition is challenging as compromised health status and functional independence can worsen. We aimed to provide an updated overview of the consequences of aging with SCI, highlighting the main challenges facing this population in a narrative review of the current literature we retrieved from the PubMed database from 2000 to 2022 on any aspect related to aging in persons with SCI. Here we address adverse circumstances that increase disability and hinder an active lifestyle, such as progressive physical deterioration, secondary health conditions, limitations in personal activity, changes in family and social support structures, aging of caregivers, and depletion of economic resources. Favorable changes are also observed, including psychosocial adjustments that improve quality of life. Additionally, various interventions are discussed to promote well-being, health, and social participation. Due to the relevance of this issue, people with SCI and all those who take care of them must have up-to-date information to carry out the necessary measures to promote healthy aging in a more inclusive social environment.

Bruxism and Botulinum Injection: Challenges and Insights

Botulinum toxin (BTA) is a bacterial-derived extract that can inhibit muscle contraction, acting directly on the absorption of acetylcholine. Thanks to this property, botulinum has been used in aesthetic and general medicine for several years. Nowadays, the use of botulinum toxin is being deepened to address the problem of bruxism. In this scoping review, the results of the studies in the literature of the last 10 years were analyzed. Indeed, 12 reports (found on PubMed, Web of Science, and Scopus, entering the keywords "BRUXISM" and "BOTULINUM TOXIN") were deemed eligible for inclusion in this review. In the studies reviewed, BTA was injected into different muscle groups: masseters, masseter and temporalis or masseter, temporalis, and medial pterygoid. Botulinum toxin injection is a viable therapeutic solution, especially in patients with poor compliance or without improvement in conventional treatment.

Intrathecal administration of botulinum toxin type a antagonizes neuropathic pain by countering increased vesicular nucleotide transporter expression in the spinal cord of chronic constriction injury of the sciatic nerve rats

Botulinum toxin type A (BoNT/A) induces direct analgesic effects in neuropathic pain by inhibiting the release of substance P, calcitonin gene-related peptide (CGRP) and glutamate. Vesicular nucleotide transporter (VNUT) was responsible for the storage and release of ATP in vivo, and one of the mechanisms underlying neuropathic pain is VNUT-dependent release of extracellular ATP from dorsal horn neurons. However, the analgesic effect of BoNT/A by affecting the expression of VNUT remained largely unknown. Thus, in this study, we aimed to elucidate the antinociceptive potency and analgesic mechanism of BoNT/A in chronic constriction injury of the sciatic nerve (CCI) induced neuropathic pain. Our results showed that a single intrathecal injection of 0.1 U BoNT/A seven days after CCI surgery produced significant analgesic activity and decreased the expression of VNUT in the spinal cord of CCI rats. Similarly, BoNT/A inhibited the CCI-induced increase in ATP content in the rat spinal cord. Overexpression of VNUT in the spinal cord of CCI-induced rats markedly reversed the antinociceptive effect of BoNT/A. Furthermore, 33 U/mL BoNT/A dramatically reduced the expression of VNUT in pheochromocytoma (PC12) cells but overexpressing SNAP-25 increased VNUT expression in PC12 cells. Our current study is the first to demonstrate that BoNT/A is involved in neuropathic pain by regulating the expression of VNUT in the spinal cord in rats.

Botulinum Toxin and Dynamic Splint Restore Grasping Function after Stroke: A Case Report

Evidence on the effectiveness of upper extremity rehabilitation post-stroke is inconclusive. We evaluated a tailored therapeutic program with dynamic splint and botulinum toxin injections for the treatment of upper extremity muscle spasticity. A case of a 43-year-old woman with chronic spastic hemiparesis after ischemic stroke with significant mobility impairment in the left upper extremity was described. A 16-week program consisted of three 50-min sessions daily and focused on grasping and releasing with and without the splint. The patient was evaluated before botulinum toxin injection and after 6, 12 and 16 weeks according to the International Classification of Functioning, Disability and Health, and included the following scales: Fugl-Meyer Upper Extremity Assessment (FMA-UE), Modified Ashworth Scale, Numerical Rating Scale (NRS), MyotonPro, Stroke Impact Scale, Box and Blocks. Photographic documentation made before and after the experiment was compared. Motor functions improved by 19.7% on FMA-UE, spasticity was reduced by one degree and pain at rest and during activity decreased by one score on NRS. A reduction in the oscillation frequency of the relaxed muscle and the stiffness of the examined muscles was observed. The patient regained grasping function. Health-related quality of life was systematically improving with a 35% increase at week 16 compared to the baseline. The combination treatment for spasticity based on botulinum toxin and SaeboFlex^® dynamic splint in a patient with chronic spastic hemiparesis reduces disability and improves quality of life. However, further research is needed to investigate the treatment results.

Utility of botulinum toxin injection for post-operative pain management after conventional hemorrhoidectomy: a systematic review and meta-analysis of clinical trials

BACKGROUND

Botulinum Toxin (BTX) has been found to have anti-spasm and analgesic effects. The utility of BTX after conventional hemorrhoidectomy remains unclear. Thus, a systematic review and meta-analysis are required to find out its utility after conventional hemorrhoidectomy.

METHODS

Using specific keywords, we comprehensively go through the potential articles on PubMed, ClinicalTrials.gov, and Europe PMC sources until March 27^th, 2022. All published studies on botulinum toxin anal sphincter injection after conventional hemorrhoidectomy were collected. We were using Review Manager 5.4 software to conduct statistical analysis.

RESULTS

Five clinical trial studies with a total of 260 patients undergoing hemorrhoidectomy were included in the analysis Our pooled analysis revealed that BTX injection after hemorrhoidectomy was associated with lower VAS at 24 h post-operative [Mean Difference -1.35 (95% CI -1.90, -0.80), p < 0.00001, I² = 0%] and shorter time to return work [Mean Difference -8.94 days (95% CI -12.57, -5.30), p < 0.00001, I² = 0%]. However, BTX injection did not differ significantly from placebo in terms of time to first defecation (p = 0.22), fecal incontinence (p = 0.91) and urinary retention incidence (p = 0.18).

CONCLUSION

BTX sphincter injection may offer some benefit after conventional hemorrhoidectomy in reducing pain from the first day after the procedure and promoting wound healing without complication. Further randomized clinical trials are still needed to confirm the results of our study.

Pain Specialist Management of Sexual Pain-II: Interventional

INTRODUCTION

Treatment of female sexual pain often requires the use of diverse modalities crossing multiple medical disciplines. Interventional procedures are important in the diagnosis and treatment of female sexual pain. Pain specialists and other medical specialties can provide these capabilities.

OBJECTIVES

To provide a current summary of the procedures used in the diagnosis and treatment of female sexual pain.

METHODS

The internet, PubMed, and the Cochrane Library were searched for relevant articles on female sexual pain within the clinical purview and scope of the practice of pain management.

RESULTS

A thorough review of the literature was conducted to include basic science studies, clinical trials, systematic reviews, consensus statements, and case reports. An effort was made to also include a sampling of information on real-world patient self-directed therapies. Descriptions of interventional procedures for the diagnosis and treatment of sexual pain were made and clinical studies reviewed. The evidence for the use of various interventional treatment strategies for sexual pain was assessed.

CONCLUSIONS

The process of care for female sexual pain employs an interdisciplinary biopsychosocial model that includes a role for interventional procedures commonly performed by pain management specialists. These specialists are a resource of knowledge, skills, and abilities that can be used to improve the care of women with chronic sexual pain.

Modern Principles of Diagnosis and Treatment in Complex Regional Pain Syndrome

BACKGROUND

Background: Complex regional pain syndrome (CRPS) is a relatively common complication, occurring in 5% of cases after injury or surgery, particularly in the limbs. The incidence of CPRS is around 5-26/100 000. The latest revision of the International Statistical Classification of Diseases and Related Health Problems (ICD-11) now categorizes CRPS as a primary pain condition of multifactorial origin, rather than a disease of the skeletal system or the autonomic nervous system.

METHODS

Method: Based on a selective search of the literature, we summarize current principles for the diagnosis and treatment of CRPS.

RESULTS

Results: Regional findings in CRPS are accompanied by systemic symptoms, especially by neurocognitive disorders of body perception and of symptom processing. The therapeutic focus is shifting from predominantly passive peripheral measures to early active treatments acting both centrally and peripherally. The treatment is centered on physiotherapy and occupational therapy to improve sensory perception, strength, (fine) motor skills, and sensorimotor integration/ body perception. This is supported by stepped psychological interventions to reduce anxiety and avoidance behavior, medication to decrease inflammation and pain, passive physical measures for reduction of edema and of pain, and medical aids to improve functioning in daily life. Interventional procedures should be limited to exceptional cases and only be performed in specialized centers. Spinal cord and dorsal root ganglion stimulation, respectively, are the interventions with the best evidence.

CONCLUSION

Conclusion: The modern principles for the diagnosis and treatment of CRPS consider both, physiological and psychological mechanisms, with the primary goal of restoring function and participation. More research is needed to strengthen the evidence base in this field.

Meta-Analysis of Effectiveness and Safety of Botulinum Toxin in the Treatment of Complex Regional Pain Syndrome

Complex regional pain syndrome (CRPS) is characterized by pain, limited range of motion, swelling, skin changes, vasomotor instability, and patchy bone demineralization. Conservative management strategies for CRPS include physical and occupational therapy, psychosocial and behavioral therapy, and pharmacotherapy. However, some patients still experience CRPS symptoms after receiving conventional treatments. Therefore, botulinum toxin (BoNT) has been applied to patients with CRPS in several trials considering its analgesic effect in musculoskeletal and neuropathic pain; however, the results were controversial. We conducted the study to explore the effectiveness and safety of BoNT in patients with complex regional pain syndrome (CRPS). A search was performed using the following electronic databases up to 19 October 2022: PubMed, Embase, and Cochrane Library. We included both randomized controlled trials and nonrandomized controlled studies involving patients with complex regional pain syndrome managed with botulinum toxin. Cochrane risk-of-bias tool and Joanna Briggs Institute Critical Appraisal Checklist were used for quality assessment for randomized controlled trials and quasi-experimental studies. Only randomized controlled trials entered the meta-analysis. The primary outcome was the visual analogue scale of pain presented as a weighted mean difference (WMD) and 95% confidence interval (CI). The secondary outcome was the risk of adverse events presented as an odds ratio (OR) with 95% CI. We analyzed eight articles with 176 patients, including three randomized controlled trials with 62 participants. The age of the patients ranged from 23.8 to 51 years old. The duration of the disease ranged from 2.2 to 11.8 years. The proportion of females ranged from 16.6% to 100%. The route of administration of BoNT included: (1) lumbar sympathetic block (LSB), (2) intramuscular injection, (3) subcutaneous or intradermal injection (SC/ID). Improvement in pain was revealed in six studies, and adverse events were all self-limited and temporary. Meta-analysis revealed a significant reduction in pain at the first follow-up between 3 weeks to 1 month after intervention (WMD, -1.036, 95% CI, -1.673 to -0.400) but not at the second follow-up between 2 to 3 months after treatment (WMD, -0.895, 95% CI, -2.249 to 0.458). Subgroup analyses between LSB and SC/ID were nonsignificant at both follow-up periods (p = 0.422, 0.139). The risk of adverse events was similar between the BoNT and control group (OR, 0.698, 95% CI, 0.136 to 3.581). In conclusion, BoNT may be effective and safe for alleviating pain in patients with CRPS. However, we could not draw definite conclusions due to small sample size and high between-study heterogeneity. The limited number of participants may conceal the possibility of serious adverse events. Further large-scale randomized controlled trials are warranted to delineate the role of BoNT in CRPS.

Outcomes of combined pyloric botulinum toxin injection and balloon dilation in dyspepsia with and without delayed gastric emptying

Background

Pyloric botulinum toxin injection has improved symptoms in children with delayed gastric emptying. We aimed to determine the clinical response to combined endoscopic intra-pyloric botulinum toxin injection and pyloric balloon dilation (IPBT-BD) in patients with dyspepsia.

Methods

Electronic medical records were reviewed to gather demographic data, symptoms, and follow-up on patients with dyspepsia. Cases were defined as those who underwent IPBT-BD in addition to their ongoing management. Controls received pharmacotherapy, behavioral intervention, or dietary management alone. Clinical response was defined as no change, partial, or complete improvement in symptoms within 12 months. Propensity score matching based on age, gender, and symptom duration was used to pair cases and controls.

Results

In total, 79 cases and 83 controls were identified. After propensity matching, 63 patients were included in each group. The mean age for cases was 14.5 ± 3.9y; 62% were females and 98% were Caucasian. Further, 83% of 46 cases and 94% of 49 controls who had scintigraphy scans showed delayed gastric emptying. After matching, 76% of cases showed partial or complete improvement compared with 49% controls within 12 months (P = 0.004). Younger children tended to respond more favorably to the procedure (P = 0.08).

Conclusions

In our propensity-matched analysis, combined IPBT-BD in addition to pharmacotherapy, behavioral, or dietary management clearly showed a benefit over these modalities alone. This favorable response lasted up to 12 months.

Intragastric injection of botulinum toxin A for weight loss: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIM

Intragastric botulinum toxin A (BTA) injection is a potential treatment for weight reduction in obese patients. Current studies yielded conflicting results. We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) to assess the efficacy of intragastric BTA injection for weight management.

METHODS

We searched several databases to identify RCTs evaluating intragastric BTA injections for obesity. We applied random-effects models for all meta-analyses due to heterogeneity in the included studies. The mean difference (MD) and 95% confidence interval (CI) were calculated for continuous outcomes.

RESULTS

A total of 6 RCTs including 192 subjects met the inclusion criteria and were included for the meta-analysis. Although the pooled data from six studies showed no difference in the absolute weight loss between intragastric BTA injection and control, subgroup analysis showed a significantly decreased absolute weight after a BTA injection dose ≥ 200 U (MD, -2.04 kg; 95% CI, -3.96 to -0.12) and after multiple injection regions in the stomach combined with diet control (MD, -4.44 kg; 95% CI, -6.54 to -2.33 kg) compared with the control. Regarding absolute weight loss, the impact of endoscopic ultrasound-guided injection and follow-up duration showed no difference. Intragastric BTA injection had a significant change in body mass index (MD, -1.25 kg/m² ; 95% CI, -2.18 to -0.32 kg/m² ) and prolonged gastric half-emptying time (MD, 11.37 min; 95% CI, -3.69 to 19.06 min).

CONCLUSION

Intragastric BTA injection is effective for obesity treatment, and adequate doses (≥ 200 U), multiple gastric injection regions, and combined diet control are crucial. However, given the small sample size and limited power, caution should be exercised.

Central Neuropathic Pain Syndromes: Current and Emerging Pharmacological Strategies

Central neuropathic pain is caused by a disease or lesion of the brain or spinal cord. It is difficult to predict which patients will develop central pain syndromes after a central nervous system injury, but depending on the etiology, lifetime prevalence may be greater than 50%. The resulting pain is often highly distressing and difficult to treat, with no specific treatment guidelines currently available. This narrative review discusses mechanisms contributing to central neuropathic pain, and focuses on pharmacological approaches for managing common central neuropathic pain conditions such as central post-stroke pain, spinal cord injury-related pain, and multiple sclerosis-related neuropathic pain. Tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and gabapentinoids have some evidence for efficacy in central neuropathic pain. Medications from other pharmacologic classes may also provide pain relief, but current evidence is limited. Certain non-pharmacologic approaches, neuromodulation in particular, may be helpful in refractory cases. Emerging data suggest that modulating the primary afferent input may open new horizons for the treatment of central neuropathic pain. For most patients, effective treatment will likely require a multimodal therapy approach.

Multidimensional Effectiveness of Botulinum Toxin in Neuropathic Pain: A Systematic Review of Randomized Clinical Trials

Although botulinum toxin (BoNT) has been suggested as a treatment to counter neuropathic pain, no previous systematic reviews investigated the multidimensional effects of BoNT on pain relief and Health-Related Quality of Life (HR-QoL). The aim of this systematic review is to summarize the current evidence on the effectiveness of BoNT treatment for neuropathic pain, and to characterize its multidimensional effectiveness in order to guide physicians in clinical practice. Five databases were systematically searched up to 4 April 2022, to identify randomized controlled trials satisfying the following criteria: adults suffering from neuropathic pain, BoNT administration, any comparator, multidimensional assessment of pain as primary outcome, HR-QoL, physical function, anxiety and depression, and sleep quality as secondary outcomes. Twelve studies were included. The multidimensional pain scales used were short-form McGill Pain Questionnaire, Neuropathic pain scale, Neuropathic Pain Symptom Inventory, International SCI Pain Basic Data Set, West Haven-Yale Multidimensional Pain Inventory, Brief Pain Inventory, and Douleur Neuropathique 4. These scales highlighted the positive effects of BoNT administration. According to the Jadad scale, all the RCTs included were high-quality studies. BoNT administration might be effectively introduced in the comprehensive management of neuropathic pain. Further research should focus on optimal and cost-effective therapeutic protocols.

Comparative Efficacy and Safety of 11 Drugs as Therapies for Adults With Neuropathic Pain After Spinal Cord Injury: A Bayesian Network Analysis Based on 20 Randomized Controlled Trials

Objective

To provide an updated analysis of the efficacy and safety of drugs for the management of neuropathic pain (NP) after spinal cord injury (SCI) based on Bayesian network analysis.

Methods

A Bayesian network meta-analysis of literature searches within PubMed, Cochrane Library, Embase, and Web of Science databases from their inception to February 21 2021 was conducted without language restrictions. Paired and network meta-analyses of random effects were used to estimate the total standardized mean deviations (SMDs) and odds ratios (ORs).

Results

A total of 1,133 citations were identified and 20 RCTs (including 1,198 patients) involving 11 drugs and placebos for post-SCI NP selected. The 5 outcomes from all 11 drugs and placebos had no inconsistencies after Bayesian network analysis. BTX-A gave the most effective pain relief for the 4 weeks, following a primary outcome. No significant differences were found among drugs with regard to adverse events of the primary outcome. Gabapentin, BTX-A, and pregabalin were found to be the most helpful in relieving secondary outcomes of mental or sleep-related symptoms with differences in SMDs, ranging from −0.63 to −0.86. Tramadol triggered more serious adverse events than any of the other drugs with differences in ORs ranging from 0.09 to 0.11.

Conclusion

BTX-A, gabapentin, pregabalin, amitriptyline, ketamine, lamotrigine, and duloxetine were all effective for NP management following SCI. Lamotrigine and gabapentin caused fewer side effects and had better efficacy in relieving mental or sleep-related symptoms caused by SCI-related NP. Tramadol, levetiracetam, carbamazepine, and cannabinoids could not be recommended due to inferior safety or efficacy.

Systematic Review Registration

[https://inplasy.com/inplasy-2020-7-0061/], identifier [INPLASY202070061].

Direct Inhibition of Microglia Activation by Pretreatment With Botulinum Neurotoxin A for the Prevention of Neuropathic Pain

Peripheral injection of botulinum neurotoxin A (BoNT/A) has been demonstrated to have a long-term analgesic effect in treating neuropathic pain. Around peripheral nerves, BoNT/A is taken up by primary afferent neurons and inhibits neuropeptide release. Moreover, BoNT/A could also be retrogradely transported to the spinal cord. Recent studies have suggested that BoNT/A could attenuates neuropathic pain by inhibiting the activation of spinal glial cells. However, it remains unclear whether BoNT/A directly interacts with these glial cells or via their interaction with neurons. Our aim here is to determine the direct effect of BoNT/A on primary microglia and astrocytes. We show that BoNT/A pretreatment significantly inhibits lipopolysaccharide (LPS) -induced activation and pro-inflammatory cytokine release in primary microglia (1 U/mL BoNT/A in medium), while it has no effect on the activation of astrocytes (2 U/mL BoNT/A in medium). Moreover, a single intrathecal pre-administration of a low dose of BoNT/A (1 U/kg) significantly prohibited the partial sciatic nerve ligation (PSNL)- induced upregulation of pro-inflammatory cytokines in both the spinal cord dorsal horn and dorsal root ganglions (DRGs), which in turn prevented the PSNL-induced mechanical allodynia and thermal hyperalgesia. In conclusion, our results indicate that BoNT/A pretreatment prevents PSNL-induced neuropathic pain by direct inhibition of spinal microglia activation.

BoNT/A alleviates neuropathic pain in osteoarthritis by down-regulating the expression of P2X4R in spinal microglia

Neuropathic pain in osteoarthritis is one of the reasons why the pain is difficult to treat, and P2X4R plays an important role in neuropathic pain. In addition, BoNT/A has been proven to have analgesic effects on both neuropathic pain and osteoarthritis, but its exact mechanism is still unknown. This study aims to investigate the relationship between the analgesic effect of BoNT/A on osteoarthritis and the expression of P2X4R in spinal cord microglia. The analgesic effect was compared between BoNT/A and compound betamethasone. Western blot analysis was used to examine the expression of P2X4R and BDNF proteins in the spinal cord. Immunohistochemistry was used to determine the cellular location of P2X4R. Mechanical allodynia and weight asymmetry were identified using the hind paw withdrawal threshold and weight bearing test. The results showed that intra-articular injection of MIA induced persistent mechanical allodynia and weight asymmetry in rats. Both BoNT/A and betamethasone could relieve pain behavior in rats, but BoNT/A had a more obvious effect and lasted longer. Furthermore, BoNT/A could reverse the MIA-induced overexpression of BDNF and P2X4R in the spinal dorsal horn. To sum up, BoNT/A is more effective than betamethasone in relieving MIA-induced osteoarthritis pain in rats, and its analgesic effect may be related to the regulation of P2X4R-mediated BDNF release in spinal microglia and the relief of neuropathic pain in osteoarthritis.

Effectiveness and Safety of Botulinum Toxin Type A in Treatment of Restless Legs Syndrome: A Systematic Review and Meta-Analysis

Our study aimed to investigate the effectiveness and safety of botulinum toxin type A in patients with restless legs syndrome. We searched electronic databases, including PubMed, Cochrane Library, and Web of Science, up to 12 June 2021, for published articles. We enrolled randomized controlled clinical trials and non-randomized controlled studies involving patients with restless legs syndrome who were treated with botulinum toxin. Quality assessment was performed using the Cochrane risk of bias tool and Joanna Briggs Institute Critical Appraisal Checklist for Quasi-Experimental Studies. As for the results, we included four articles comprising 62 participants, two studies were randomized controlled trials. Improvement in International Restless Legs Syndrome Study Group (IRLSSG) rating scale was observed in three studies. Adverse events were temporary and self-limited. Meta-analyses were performed, including the two randomized controlled trials with 27 participants. Compared with placebo, botulinum toxin injection significantly reduced scores of IRLSSG rating scale (SMD, −0.819, 95% confidence interval [CI], −1.377 to −0.262). A total of 11.8% (95% CI, 0.7–72.4%) of patients reported at least one adverse event. In conclusion, botulinum toxin injection may relieve restless legs syndrome related symptoms. However, decisive conclusions cannot be drawn because of the small number of patients included in our meta-analysis. Large-scale, randomized controlled trials are warranted to discover the optimal dose, safety, and long-term effect of intervention with botulinum toxin type A for patients with restless legs syndrome.

The Mechanisms of Action of Botulinum Toxin Type A in Nociceptive and Neuropathic Pathways in Cancer Pain

BACKGROUND

Botulinum toxin type A (BoNT-A) is widely employed for cosmetic purposes and in the treatment of certain diseases such as strabismus, hemifacial spasm and focal dystonia among others. BoNT-A effect mainly acts at the muscular level by inhibiting the release of acetylcholine at presynaptic levels consequently blocking the action potential in the neuromuscular junction. Despite the great progress in approval and pharmaceutical usage, improvement in displacing BoNT-A to other pathologies has remained very limited. Patients under diagnosis of several types of cancer experience pain in a myriad of ways; it can be experienced as hyperalgesia or allodynia, and the severity of the pain depends, to some degree, on the place where the tumor is located. Pain relief in patients diagnosed with cancer is not always optimal, and as the disease progresses, transition to more aggressive drugs, like opioids is sometimes unavoidable. In recent years BoNT-A employment in cancer has been explored, as well as an antinociceptive drug; experiments in neuropathic, inflammatory and acute pain have been carried out in animal models and humans. Although its mechanism has not been fully known, evidence has shown that BoNT-A inhibits the secretion of pain mediators (substance P, Glutamate, and calcitonin gene related protein) from the nerve endings and dorsal root ganglion, impacting directly on the nociceptive transmission through the anterolateral and trigeminothalamic systems.

AIM

The study aimed to collect available literature regarding molecular, physiological and neurobiological evidence of BoNT-A in cancer patients suffering from acute, neuropathic and inflammatory pain in order to identify possible mechanisms of action in which the BoNT-A could impact positively in pain treatment.

CONCLUSION

BoNT-A could be an important neo-adjuvant and coadjuvant in the treatment of several types of cancer, to diminish pro-tumor activity and secondary pain.

Botulinum Neurotoxin Therapy for Depression: Therapeutic Mechanisms and Future Perspective

Depression is one of the most common mental disorders, which causes global burden. Antidepressants and psychotherapies are the mainstay of treatment for depression, which have limited efficacy. Thus, alternative approaches for preventing and treating depression are urgently required. Recent clinical trials and preclinical researches have clarified that peripheral facial injection of botulinum neurotoxin type A (BoNT/A) is a rapid, effective and relative safe therapy for improving some symptoms of depression. Despite its safety and efficacy, the underlying therapeutic mechanisms of BoNT/A for depression remains largely unclear. In the present review, we updated and summarized the clinical and preclinical evidence supporting BoNT/A therapy for the treatment of depression. We further discussed the potential mechanisms underlying therapeutic effects of BoNT/A on depression. Notably, we recently identified that the anti-depressant effects of BoNT/A associated with up-regulation of 5-HT levels and brain-derived neurotrophic factor (BDNF) expression in the hippocampus in a preclinical mouse model. In summary, these studies suggest that BoNT/A therapy is a potential effective and safe intervention for the management of depression. However, fundamental questions remain regarding the future prospects of BoNT/A therapy, including safety, efficacy, dose-response relationships, identification of potential predictors of response, and the precise mechanisms underlying BoNT/A therapy.

Effects of botulinum toxin A on endometriosis‑associated pain and its related mechanism

Endometriosis (EMS) is a common disease in women aged 25–45 years, and pain is the main clinical symptom. The primary clinical treatment is surgical excision and drug therapy targeting the ectopic lesions, but these have not been very effective. Botulinum neurotoxin serotype A (BTX-A) has been reported to be useful in the treatment of pain in a variety of diseases. Based on this, the aim of the present study was to explore the therapeutic effect and mechanism of BTX-A on EMS. A model of nerve injury induced by oxygen glucose deprivation (OGD) was constructed in PC12 cells and EMS mice. Model cells and mice were treated with different concentrations of BTX-A to observe the changes in pain behavior, to detect cell viability and the secretion of norepinephrine (NE) and methionine enkephalin (M-EK) in cells and the spinal cord, and to evaluate the expression of apoptosis-related molecules in spinal cord nerves. The results revealed that BTX-A significantly reduced the amount of writhing in model mice, enhanced the activity of PC12 OGD cells, increased the secretion of NE and M-EK in model cells and the spinal cord of mice, and decreased the apoptosis of neural cells in the spinal cord of the model mice. Therefore, it was hypothesized that BTX-A may alleviate the pain induced by EMS by increasing the secretion of analgesic substances and promoting the repair of nerve injury. The present study provided a theoretical basis for the treatment of pain induced by EMS.

Central pain syndromes

The management of pain in persons with neurological injuries is challenging and complex. A holistic view and clinical approach are necessary when addressing pain in patients with neurological impairment because interpreting signs and symptoms and deciphering sources of pain is never a straightforward process. This problem is further magnified with the management of central pain syndromes. The best approach is to have a good understanding of the clinical characteristics commonly found in this patient population, in particular for patients with stroke, multiple sclerosis (MS), or spinal cord injury (SCI), as central pain manifests differently between these groups. This paper will focus on the history, clinical presentation, pathophysiology, assessment, and treatment of central pain in patients with these types of neurological conditions. In addition to being at risk for a decline in quality of life, patients with pain syndromes are also prone to adverse responses to treatments (e.g., opioid addiction). It is therefore important to methodically analyze the similarities and differences between patients with different pain syndromes.

Diagnosis, Treatment, and Management of Dejerine-Roussy Syndrome: a Comprehensive Review

PURPOSE OF REVIEW

Post-stroke pain represents a complex condition with few standardized diagnostic criteria. As such, the array of symptoms is often difficult to categorize and diagnose. Central post-stroke pain (CPSP), also known as Dejerine-Roussy syndrome, presents as painful paresthesia in any part of the body that is usually coupled with sensory abnormalities.

RECENT FINDINGS

In patients who had experienced a cerebrovascular accident, CPSP typically affects the same areas of the body that are also impacted by the general motor and sensory deficits that result from stroke. Though it is generally debated, CPSP is thought to result from a lesion in any part of the central nervous system. Pain usually presents in the range of 3-6 months after the occurrence of stroke, manifesting contralaterally to the lesion, and most commonly involving the upper extremities. For the most accurate diagnosis of CPSP, a thorough history and clinical examination should be supplemented with imaging. Infarcted areas of the brain can be visualized using either CT or MRI. First-line treatment of CPSP is pharmacologic and consists of a three-drug regimen. Despite this, CPSP is often refractory to medical management producing only modest pain reduction in a limited subset of patients. Adverse effects associated with pharmacologic management of CPSP and frequent recalcitrance to treatment have driven alternative minimally invasive methods of pain control which include transcranial stimulation, deep brain stimulation, and neuromodulation. The aim of this review is to provide a comprehensive update to recent advances in the understanding of the treatment and management of CPSP.

Celiac plexus block with botulinum toxin in severe chronic pancreatitis-A case report

WHAT IS KNOWN AND OBJECTIVE

The botulinum toxin (BoNT) has been widely used for various conditions associated with pain.

CASE DESCRIPTION

Here, we report a case where celiac plexus block (CPB) with BoNT relieved intractable chronic pancreatic pain without complications. CPB was performed at the L1 level under fluoroscopic guidance, and 50 IU BoNT was injected on each side. After 15 weeks, pain was decreased to 0/10 on a visual analogue scale, without opioids or tramadol.

WHAT IS NEW AND CONCLUSION

Our case demonstrates the efficacy of CPB with BoNT in intractable pain due to severe chronic pancreatitis.

Botulinum toxin type A ameliorates adjuvant-arthritis pain by inhibiting microglial activation-mediated neuroinflammation and intracellular molecular signaling

Chronic inflammatory pain is a serious clinical problem caused by inflammation of the joints and degenerative diseases and greatly affects patients' quality of life. Persistent pain states are thought to result from the central sensitization of nociceptive pathways in the spinal dorsal horn. Spinal microglia-mediated neuroinflammation plays a pivotal role in the development and maintenance of the central sensitization of chronic inflammatory pain. Botulinum toxin type A (BoNT/A) was recently reported to have analgesic and anti-inflammatory effects. However, the precise mechanism underlying its analgesic effect remains unclear. Although several studies have reported that BoNT/A could regulate neuroflammation, the reduction of neuroinflammation regulated by BoNT/A in chronic inflammatory pain in experimentally induced arthritis has not been reported. The aim of this study was to investigate whether BoNT/A could alleviate adjuvant-arthritis pain via modulating microglia-mediated neuroinflammation and intracellular molecular pathway. The pain behavioral tests were performed before and after CFA immunization as well as after BoNT/A injection. Western blotting and immunofluorescence staining were used to assess the changes of microglial activation markers (ionized calcium binding adaptor molecule 1, IBA-1) and phosphorylation of P38MAPK (P-p38MAPK) in the lumbar spinal cord. TNF-αand P2X4R gene expression were studied by real-time reverse transcriptase-polymerase chain reaction (RT-PCR). The results showed that (1) the activation of spinal microglia can be continued till 21 days after CFA injection, which suggested its role in the development and maintenance of chronic inflammatory pain. (2) The intra-articular administration of a single effective dose of BoNT/A (5U/10 U) on day 21 after CFA injection significantly reduced nociceptive behaviors and decreased protein overexpression and immunoreactivity for IBA-1 and P-p38MAPK in CFA induced rat. Simultaneously, BoNT/A (5 U) also inhibited the increase in TNF-α mRNA and P2X4R mRNA expression induced by CFA injection. These results suggested that BoNT/A is a potential therapeutic agent for relieving the neuroinflammation that occurs in chronic inflammatory pain by inhibiting the activation of microglial cells and the release of microglia-derived TNF-α. This effect is likely mediated by inhibiting the activation of the P2X4R-P38MAPK signaling pathways in spinal microglial cells.

Healing hand ulcers caused by focal spasticity

Spasticity is a common manifestation of many upper motor neuron lesions such as stroke, traumatic brain injury, and multiple sclerosis. In some cases, spastic fingers in the hand press hard into the palm, resulting in skin breakdown and atypical pressure ulcerations. We treated 10 such patients living in the nursing homes with long-standing treatment-resistant hand ulcers in our spasticity clinic first, with Botulinum toxin A (BoNTA) injection into the spastic muscles followed by dressing, splinting, and hand therapy. These ulcers failed to respond to standard treatment, causing significant pain, offensive smell, increased carer burden, and difficulty in maintaining hygiene as hands could barely be opened for dressing and therapy. We noted complete healing of ulcers with significant improvement in the following outcome measures-Modified Ashworth Scale for spasticity, Visual Analog Scale for pain, pressure ulcer grading for the ulcers, Fingertip to Palm distance for hand opening, Carer Burden Scale, and in the Goal Attainment Scale pre, 4 weeks, and 3 months postinjection with P values of .003, .003, .004, .005, .004, and .004, respectively. Reducing spasticity with BoNTA should be the first step in treating hand ulcerations caused by focal spasticity, followed by dressing, splinting, and hand therapy.

Effect of Botulinum Toxin A on Bladder Pain-Molecular Evidence and Animal Studies

Botulinum toxin A (BTX-A) is a powerful neurotoxin with long-lasting activity that blocks muscle contractions. In addition to effects on neuromuscular junctions, BTX-A also plays a role in sensory feedback loops, suggesting the potentiality for pain relief. Although the only approved indications for BTX-A in the bladder are neurogenic detrusor overactivity and refractory overactive bladder, BTX-A injections to treat bladder pain refractory to conventional therapies are also recommended. The mechanism of BTX-A activity in bladder pain is complex, with several hypotheses proposed in recent studies. Here we comprehensively reviewed properties of BTX-A in peripheral afferent and efferent nerves, the inhibition of nociceptive neurotransmitter release, the reduction of stretch-related visceral pain, and its anti-inflammatory effects on the bladder urothelium. Studies have also revealed possible effects of BTX-A in the human brain. However, further basic and clinical studies are warranted to provide solid evidence-based support in using BTX-A to treat bladder pain.

Botulinum toxin infiltrations versus local anaesthetic infiltrations in pelvic floor myofascial pain: Multicentre, randomized, double-blind study

BACKGROUND

Many studies have demonstrated a link between pelvic floor myofascial syndromes and chronic pelvic pain. Botulinum toxin has been extensively used for several years in the field of pain, especially due to its action on muscle spasm. However, the efficacy of botulinum toxin in the context of chronic pelvic pain remains controversial.

OBJECTIVES

This multicentre, randomized, controlled, double-blind study was designed to compare the efficacy of botulinum toxin and local anaesthetic (LA) injection versus LA injection alone for pelvic floor myofascial syndrome and chronic pelvic pain.

METHODS

According to the number of painful trigger points detected on physical examination, patients received from 1 to 4 injections of botulinum toxin with LA (BTX) or LA alone. The primary endpoint was Patient Global Impression of Improvement (PGI-I) score on day 60 after infiltration. Secondary endpoints were pain intensity, number of painful trigger points on palpation, analgesic drug consumption and quality of life.

RESULTS

We included 80 patients, 40 in each group. This study failed to demonstrate a significant difference between the 2 groups on day 60 in the primary endpoint or secondary endpoints (PGI-I score≤2=20% [LA] versus 27.5% [BTX], P=0.43). However, both groups showed significant alleviation of global pain.

CONCLUSION

This study does not justify the use of botulinum toxin in the context of chronic pelvic pain with myofascial syndrome but does justify muscle injections with LA alone. ClinicalTrials.gov: NCT01967524.

Therapeutic Approaches for Peripheral and Central Neuropathic Pain

Neuropathic pain is a chronic secondary pain condition, which is a consequence of peripheral or central nervous (somatosensory) system lesions or diseases. It is a devastating condition, which affects around 7% of the general population. Numerous etiological factors contribute to the development of chronic neuropathic pain. It can originate from the peripheral part of the nervous system such as in the case of trigeminal or postherpetic neuralgia, peripheral nerve injury, painful polyneuropathies, or radiculopathies. Central chronic neuropathic pain can develop as a result of spinal cord or brain injury, stroke, or multiple sclerosis. As first-line pharmacological treatment options, tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and gabapentinoids are recommended. In trigeminal neuralgia, carbamazepine and oxcarbazepine are the first-choice drugs. In drug-refractory cases, interventional, physical, and psychological therapies are available. This review was structured based on a PubMed search of papers published in the field from 2010 until May 2019.

The Botulinum Treatment of Neurogenic Detrusor Overactivity: The Double-Face of the Neurotoxin

Botulinum neurotoxin (BoNT) can counteract the highly frequent involuntary muscle contractions and the uncontrolled micturition events that characterize the neurogenic detrusor overactivity (NDO) due to supra-sacral spinal cord lesions. The ability of the toxin to block the neurotransmitter vesicular release causes the reduction of contractions and improves the compliance of the muscle and the bladder filling. BoNT is the second-choice treatment for NDO once the anti-muscarinic drugs have lost their effects. However, the toxin shows a time-dependent efficacy reduction up to a complete loss of activity. The cellular mechanisms responsible for BoNT effects exhaustion are not yet completely defined. Similarly, also the sites of its action are still under identification. A growing amount of data suggest that BoNT, beyond the effects on the efferent terminals, would act on the sensory system recently described in the bladder mucosa. The specimens from NDO patients no longer responding to BoNT treatment displayed a significant increase of the afferent terminals, likely excitatory, and signs of a chronic neurogenic inflammation in the mucosa. In summary, beyond the undoubted benefits in ameliorating the NDO symptomatology, BoNT treatment might bring to alterations in the bladder sensory system able to shorten its own effectiveness.

A Prospective Observational Cohort Study on Pharmacological Habitus, Headache-Related Disability and Psychological Profile in Patients with Chronic Migraine Undergoing OnabotulinumtoxinA Prophylactic Treatment

Chronic Migraine (CM) is a disabling neurologic condition with a severe impact on functioning and quality of life. Successful therapeutic management of patients with CM is complex, and differences in therapeutic response could be attributable to genetically determined factors, sensitivity to pharmacological treatment, psychosocial and relational factors affecting the patient’s compliance and approach on the therapeutic treatment. The aim of this prospective observational study was to explore self-efficacy, coping strategies, psychological distress and headache-related disability in a cohort of 40 patients with CM (mean age: 46.73; standard deviation 13.75) treated with OnabotulinumtoxinA and the relationship between these clinical and psychological aspects and acute medication consumption during OnabotulinumtoxinA prophylactic treatment. Patients presented an overall significant reduction in the Headache Index (HI) (p < 0.001), HI with severe intensity (p = 0.009), and total analgesic consumption (p = 0.003) after the prophylactic treatment. These results are in line with the literature. Despite this, higher nonsteroidal anti-inflammatory drugs consumption was associated with higher psychological distress, higher HI with severe and moderate intensity, and worse quality of life. Conversely, triptans consumption was correlated with HI of mild intensity, and problem-focused coping strategies. To conclude, the psychological profile, and in particular, the psychological distress and specific coping strategies might influence the self-management of acute medication.

Pain in cervical dystonia and the antinociceptive effects of botulinum toxin: what is currently known?

Pain is the most common and disabling non-motor symptom in cervical dystonia (CD). Up to 88.9% of patients report pain at some point in the course of the disease. It is still a matter of debate whether CD-related pain originates only from prolonged muscle contraction. Recent data suggest that the alterations of transmission and processing of nociceptive stimuli play a crucial role in pain development. Botulinum toxin (BT) is the first-line therapy for CD. Despite fully elucidated muscle relaxant action, the antinociceptive effect of BT remains unclear and probably exceeds a simple decompression of the nerve fibers due to the reduction in muscle tone. The proposed mechanisms of the antinociceptive action of BT include inhibition of pain mediator release, inhibition of membrane sodium channels, retrograde axonal transport and impact on the other pain pathways. This article summarizes the current knowledge about the antinociceptive properties of BT and the clinical analgesic efficacy in the treatment of CD patients.

Efficacy of Botulinum Toxin A for Treating Cramps in Diabetic Neuropathy

OBJECTIVE

Muscle cramps occur in >50% of diabetic patients and reduce the quality of life. No effective treatment is available. We evaluated the clinical effectiveness of botulinum toxin A (BTX-A) injections for treating cramps in diabetic patients with neuropathy.

METHODS

This single-center, double-blind, placebo-controlled perspective study investigated the efficacy and safety of BTX-A intramuscular injection for treating calf or foot cramps refractory to common pharmacological drugs. Fifty diabetic patients with peripheral neuropathy and cramps were randomly assigned to 2 matched groups. BTX-A (100 or 30 units) or saline was injected on each side into the gastrocnemius or the small flexor foot muscles. Changes in pain intensity (primary outcome) and cramp frequency were evaluated over the course of 20 weeks after BTX-A administration. Cramp interference in daily life and the electrophysiological cramp threshold frequency were also measured. The treatment was repeated 5 months after first injection in 19 responders.

RESULTS

All outcome measures improved significantly after BTX-A compared with placebo. The changes with respect to baseline were already significant after 1 week and persisted up to week 14. Only 5 of 25 (20%) patients were nonresponders (<50% decrease of the primary outcome). The responses to a second BTX-A injection provided results similar to the first administration. Mild pain at the injection site (4/25 cases) was the only adverse event, and it disappeared within 2 to 3 days.

INTERPRETATION

Local BTX-A infiltration is an efficacious and safe procedure for obtaining a sustained amelioration of muscle cramps associated with diabetic neuropathy. Ann Neurol 2018;84:682-690.